NEW YORK (CBSNewYork) — The TCS New York City Marathon is happening this coming Sunday, and will draw people from all over the world.

Safety is always a priority for the marathon, but the terror attack in Lower Manhattan on Tuesday brings it to another level. So the NYPD is adding a lot of security along the route to protect runners and spectators.

“We have the biggest counterterrorism force of any police force in the nation. It is out in very strong numbers so people can see it. It is a deterrent force,” Mayor Bill de Blasio told “CBS This Morning.” “We are, in this city, very comfortable putting out larger numbers of police officers with heavy gear, with heavy weapons to send the message, ‘Don’t try anything here.'”

But concerns about security are high, especially with the marathon just days away. The event is expected to attract over 51,000 runners and more than 2 million spectators along the streets across the five boroughs. The attack postponed the annual ceremonial painting of the finish line Wednesday, but the marathon is scheduled to go on as planned this Sunday, under tighter security.

And as CBS2’s Ali Bauman reported, record security is planned for security – both on the ground and above, with officers watching from rooftops and helicopters. Some of the security was already getting set up Wednesday.

“There will be a huge police presence, a lot you will see and a lot you won’t see,” de Blasio said.

NYPD Chief Carlos Gomez detailed the enhanced security measures for the marathon during a press conference Wednesday. As has become custom for large events in New York such as the Macy’s Thanksgiving Day Parade and the New Year’s Eve ball drop, Gomez said sand trucks will park along the perimeter.

“It’s going to be a very safe event,” Gomez said. “We’ve added more sand trucks, more blocker vehicles — it will be the most-ever deployed at this event. We’ve more than doubled our rooftop observations posts as well as our counter sniper teams from the Emergency Services Unit throughout the boroughs, not just here in Manhattan.”

Gomez said officers from the Emergency Services Unit, Strategic Response Group and Critical Response Command will be at fixed locations along the route but will be mobilized as needed.

There will be more heavy weapons teams, uniformed and plainclothes officers, K-9 units, counterterrorism officers patrolling the route.

The NYPD’s Aviation Unit will also use helicopters to patrol from above.

“They’ll survey rooftops, as well as the route,” Gomez said.

De Blasio said the city has learned “that we have to constantly reassess where we put up our physical barriers.”

“I think it’s important for the race to do it, and I believe that it’s important for all New Yorkers to come and participate,” said marathon volunteer Joseph Negrelli.

Fernando Rondon of Peru will be among those running on Sunday, even though the attack on Tuesday gave him pause.

“I think it’s more important to show them that we’re not afraid,” Rondon said.

In the meantime, a portion of the West Side Highway path reopened Wednesday. People were making good use of it, undeterred by the attack just a day before, 1010 WINS’ Carol D’Auria reported.

“I feel safe. I think, well what should I do? So I just go on,” said one man from Germany who’s training for Sunday’s marathon.

Another man said he walks the path every day and won’t stop now.

“It’s such a random thing and it happens who knows where and who knows when that I think interrupting your daily routine out of fear is the wrong way to look at it,” he said, adding we can’t blame the hatred on the world on the immigrants, like Saipov.

Following the May 18 incident in Times Square, in which a man allegedly plowed his car into pedestrians on a sidewalk, de Blasio said the city “made physical changes and we will continue to make physical changes when it comes to the big parades and events.”

De Blasio noted vehicles are no longer permitted to cross parade routes and blocker trucks are also used at large events such as the New Year’s Eve celebration in Times Square and the Thanksgiving Day Parade.

“This is an ever-evolving situation but I can tell you from the New York City perspective, our formula is simple: put up a lot of people out, put a lot of officers out, well-armed to send a deterrent message,” de Blasio said.

The mayor and Gov. Andrew Cuomo also stressed one of the best tools in fighting these attacks is intelligence.

“All of our evidence from yesterday points to a lone wolf. These are the hardest cases to predict because they don’t have the same type of connections,” Cuomo said. “People have to remember for every one attack there are dozens and dozens that are prevented and found out through intelligence.”

The governor and mayor are urging the public to report any suspicious activity to authorities.

“The attacks that have been stopped, which we don’t talk about, were based on everyday people who went to an police officer and shared information,” de Blasio said. “If you see anything that might be suspicious, bring it to a police officer. Because it can be the difference. It can be the life saver.”

Officials remind the public that if you see something, say something.

“If you see something out there that doesn’t look right, if it makes you uncomfortable, you have an obligation to make a call or to flag down a police car,” NYPD Commissioner James O’Neill said. “At least give us the opportunity to investigate that.”